Some people urinate when they’re frightened. Others can’t when they’re nervous.
Bladder control requires a sophisticated interplay of brain regions. An area of the brainstem known as the pontine micturition center is in constant contact with the bladder. It knows when pressure is building, and makes the preliminary decision to void. Thankfully, this area doesn’t have exclusive control over our bathroom habits, or we’d urinate whenever (and wherever) our bladders become full. The prefrontal cortex can override the desire to pee by sending an inhibitory signal to the brainstem. Under stressful conditions, however, the inhibitory signals from the frontal lobe can themselves be overridden by the limbic system, a combination of brain areas that controls the famous “fight or flight” response. When we become stressed or anxious, electrical signals from the limbic system become so intense that the brainstem has trouble following the frontal lobe’s commands. That’s why many people urinate more frequently before important exams or in the starting corral of a marathon. In life-threatening situations, the limbic system’s orders become so urgent that you can’t even make it to the bathroom.